Stoker



w. D. BURTON 2,033,919

STOKER Maf-Ch 17, 1936.

Filed Aug'. 5' 1931 Patented Mar. 17, l936r` UNITED STATES STOKER Warren Dean Burton, Goshen, Ind., assignor to Combustioneer, Inc., Goshen, Ind., a. corporation of Illinois Application August 3, 1931, Serial No. 554,734 14 claims. (ci. 11o-4s) 'I'he invention relates generally to mechanical stokers, and is particularly applicable to stokers of the underfeed type.

A general object of the invention is to provide a new and improved structure of this character which is sturdy and simple in construction, is adaptable for operation with all types of fuel, and which efliciently produces total combustion of the fuel.

Another object of the invention is to provide in a machine of this character means for efficiently supplying a large volume of air for combustion without producting what is known as fly-ash". This fly-ash is the light, powderyparticles of ash which, in stokers supplied with air under pressure for combustion purposes, is apt to be blown from the fire pot. Heretofore, flyash has been partially controlled by limiting the pressure of the air supplied for combustion,

which method is obviously inefficient.

A further object of the invention is to provide a tuyre structure which, in construction, is divided into zones of high and low air pressure, and which embodies an arrangement of parts whereby air under the highest pressure' to be `used may be supplied to the tuyre zone of high pressure, while a portion of such air is reduced in presp sure and is diverted to the tuyre zone of low pressure.

that the stoker may be operated under greater pressure than could heretofore be employed, thereby insuring faster and more complete combustion of fuel while fly-ash is substantially, if

not entirely, eliminated.

Another object of the invention is to provide, in a stoker, a movable member surrounding the upper rim of the re pot and corresponding to a."dead plate'which member is arranged to facilitate the discharge of ashes and embodies 4,0 a means for preventing the discharge oi unburned particles of fuel therewith.

In conjunction with the foregoing, an object of the invention resides in the provision of a movable member of this nature which may be readily removed from the structure for repair or for replacement by another member which may be of different character to adapt the device for operation with e. different fuel.

A further object of the invention is to provide 5o a new and improved means for removing ashes from the retcrt as they accumulate, which means includes a feed screw so arranged with respect' to the retort that gasesor the like cannot escape past or through said screw.

55 Other objects and advantages will become apparent in the following description and from the accompanying drawing, in which:

Figure 1 is a View in elevation of a retort embodying the features of the invention. parts (m thereof being shown in central vertical section,

feed type.

The advantage of such a structure is v Fig. 2 is a plan view of said retort.

Fig. 3 is a fragmentary vertical section onan enlarged scale taken centrally of the retort.

Fig. 4 is a fragmentary' section showing a de tail of construction and is taken on the line 4 4 5 of Fig. 3.

While the invention is susceptible of various modifications and alternative constructions, I have shown in the drawing and will herein described in detail the preferred embodiment, but 10 itis to be understood that I do not thereby intend to limit the invention to the specific form disclosed, but intend to cover all modifications and alternative constructions falling within the spirit and scope of the invention as expressed 15 in the appended claims.

While the present invention is illustrated and will be described in connection with a stoker of the underfeed type, it will be understood that many of the features of the invention are ap- 20 plicable to types of stokers other than the under- With particular reference to the drawing, I0 designates the walls of a furnace or the like within the lower portion of which the stoker is located. In this instance, the stoker 25 is circular in shape and embodies a central fire pot comprised of a trough I I and a. tuyre structure I2 superimposed thereon. In operation, fuel is supplied to the fire pot through the trough I I by a-suitably driven feed screw I3 turning in a 30 conveyer duct I 3a. A supply hopper or the like (not shown) delivers fuel to the feed screw at some point remote from the retort. The lower portion of the fire pot, which in the present form includes substantially all of the trough, is en- 35 closed by a surrounding vertical wail It spaced from the trough and providing an air distributing chamber I5 thereabout. Air under pressure is supplied to this chamber from any suitable source (not shown) through an air duct It.

The tuyre structure I2 is supported largely by the trough and also by the wall I t. In construction, the tuyre structure comprises a number of annular tuyre rings I'I of gradually in- 'oreasing diameters arranged to be mounted one 45 upon the other with the lower ring resting upon an out-turned flange I8 (Fig. 3) provided on the rim of the trough. Each ring is supported in spaced relation to the next lower ring by such means as a numberof substantially equidistant lugs I9 whereby tuyre openings are provided between the'rings through which air' is delivered to the fuel within the fire pot. In cross section, each ring (except the lowermost one) increases in thickness from outer to inner diameter, with the slope occurring on the bottom face of each ring. `This provides a restricted tuyre opening or air passageway between adjacent rings. The inner. faces of the rings are preferably beveled from top to bottom as at 2t so thatthe tuyre t0 openings in cross section are generally Venturishaped and have substantially the effect of a venturi on air passing therethrough. Thus, coinplete diifusion of air throughout the fuel mass is obtained. i

The wall 4 supports, on its upper edge, a cylindrical frame member 2| which extends upwardly above the position occupied by the upper one of the tuyre rings. 'I'he frame member 2| is roughly L-shaped in cross-section and is supported on the wall I4 through an abutment of the horizontal leg of the frame with an inturned horizontal flange 22 formed on the wall |4. Suitable securing means (not shown) may be employed rigidly to unite the parts.

One purpose of the frame 2| is to support and maintain the tuyre rings in place. To this end, an annular member 23 constituting the rim of the fire pot is provided, which rim is channel-shaped. The inner side of the rim is of substantial width, provides a continuation of the tuyre structure, and is spaced from the upper tuyre ring by'lugs 24 (Fig. 3) to form another series of tuyre openings between the rim and the upper ring- The rim straddles the upper edge of the frame member 2| and is secured thereto to hold the parts rigidly together. Preferably, the rim and the frame member are secured together in a manner which permits the rim to be readily removed from the assembly.

A preferred form of securing means comprises the following structure: The rim 23, at spaced intervals about the inner leg thereof, has a plurality of integrally formed lugs 25 (Figs. 3 and 4) thereon which extend horizontally into the channel of the rim. The frame 2|, adjacent its upper edge, has a corresponding number of bosses 26 formed on the inner surface thereof. 'Ihe bosses 26, as may be clearly seen in Fig. 4, are of substantial length and at one side are cut away to form a sloping surface 21 which terminates abruptly at a shoulder 28. This arrangement of parts allows the rim 23 to be properly located with respect to the tuyre rings and the frame 2 I, after which a slight rotation of the rim brings the lugs 25 thereon into engagement with the tapering surfaces 21, which engagements lock the rim and frame together. 'I'his rotational locking engagement is, as may be seen in Fig. 4, limited by the engagement of the lugs 25 with the shoulders 28. If desired, a layer of sealing ma.- terial 29 may be interposed between the abutting surfaces of the rim and frame.

Each of the tuyre rings I1 is provided with a number of outwardly and radially extending bosses 30 which preferably constitute continuations of the spacing lugs i9 and extend substantially into abutment with the frame 2|, thereby t? prevent lateral displacement of the tuyre r ngs.

It will be evident from the foregoing that, when air under pressure is supplied from the conduit I6 to the distributing chamber I5, the air may pass upwardly to the tuyre openings through the passageway defined by the frame 2| and the tuyre rings. Heretofore the pressure under which the air may be admitted has been limited by the amount of ily-ash produced thereby. This ily-ash, of course, is produced only from the upper surface of the fuel bed where the air blast encounters the entirely consumed and light particles of ash. The present invention eliminates the production of fly-ash by providing a means associated with the tuyre structure which provides azone of high air pressure throughout the lower portion of the tuyre structure and a zone of low air pressurethroughout the upper portion of the structure.

With reference to Fig. 3, an intermediate one of the tuyre rings, which ring is herein indicated as |1, is of such width that the ring extends to a point adjacent but slightly spaced from the frame 2| This ring, therefore, prevents the free passage of air to the tuyre openings above the ring I1.. I'he clearance 3| between the outer periphery of the ring I1'A is predetermined to allow a proper amount of air to pass therebetween to the upper tuyre openings, the pressure of the air, of course, being reduced by the restricted opening. Moreover, the size of the tuyre openings above the ring I1 is smaller than that of the other openings to further restrict the flow of air into the fuel bed. As a consequence, the tuyre openings below the ring I1* are supplied with air under full pressure and constitute a zone of high air blast, while the tuyre openings above the ring I1'l receive air under lower or reduced pressure and form a zone of low air pressure. 'I'l'iuaalr under a greater pressure than could normally be used, may be supplied to the lower portion of the tuyre structure to insure a complete and efficient combustion of the fuel, while the injection of air under low pressure throughout the upper portion of the tuyre structure provides an ample quantity of air for combustion purposes f while substantially eliminating or, at least, reducing to a minimum the creation of fly-ash.

The present device embodies an improved means for discharging ashes from the fire pot and for removing such discharged ashes from the :2.

retort. As shown in Fig. 3, the frame 2| is encircled by a concentrically arranged ring 32, the lower edge of which is loosely supported by the horizontal portion of the frame 2|. The ring extends upwardly into a position adjacent the upper portion of the rim 23 and has an upwardly facing shoulder 32e underlying the outer leg of the rim 23 to maintain the ring in place. An annular grate member 33 is mounted upon the upper edge of the ring 32 for detachment therefrom as by means of a plurality of lugs 34 (Fig. 2) formed on the grate 33 and engaging recesses 35 provided in the edge of the ring 32.

Theouter periphery of the grate 33 has a series of notches 35 formed therein to facilitate the discharge of ash over the edge of the grate. The upper surface of the grate carries a plurality of peripherally spaced elongated ribs 31 (Figs. 1 and 2) disposed angularly with respect to the radius of the grate and extending substantially from the outer to the inner margins thereof. The grate, which is rotatably driven by means to be hereinafter described, carries the ribs 31 therewith, which ribs act to engage and break up the upper portion of the bed of coals and ash issuing from the nre pot over the rim 23. Further, the angular relationship of the ribs is such that, in the rotation of the grate, the larger particles of the material, which contain substantially all of the unconsumed fuel, are engaged thereby and are moved toward the center of the firelpot. The action of the ribs in both breaking up large pirticles of material and moving the larger particles inwardly produces an efficient operation of the device in that practically no unburned fuel can be discharged with the ashes. By locating the walls of the furnace closely adjacent to the periphery of the grate, the size of the particles of ash which can be discharged over the grate may be limited and further eliminate the possibility of the passage ofunburned particles of fuel from the fire pot.

As ashes are discharged from the grate, they fall into the space provided between the walls I0 of the furnace and the wall i4 of the air chamber. These ashes are allowed to accumulate in this space until substantially all of the wall I4 is covered, so that the ashes form a seal about the lower portion of the retort to prevent the escape of gases therefrom. l

For removing an excess of ashes from within the furnace, the following structurels provided. The ring 32 carries a plurality of radially and outwardly. extending plates 38, the outer edges of which are positioned adjacent to the walls I0 of the furnace. As the ring 32 and grate 33 are rotated, these plates 38 engage the excess of ashes and convey them to a common removal point. This removal point is herein designated by an ash conveyer screw 39 (Fig. 1) of customary construction, which is journaled for rotation with one end of the conveyer screw extending into the furnace and located in the space between the wall Il! and the opposed wall I4. The inner end of the conveyer screw is disposed in an upwardly openingtrough 40 which, for convenience, may be secured as at 4I to the wall i4. Ashes delivered to the conveyer screw by the plates 38 will be removed thereby from the furnace through a conveyer du'ct 42 to a disposal point. The conveyer screw is driven in any suitable manner (not shown). By locating the conveyer screw externally of .the retort structure itself, the natural draft ofthe burner will prevent f gases from escaping from the furnace through the ash conveyer screw, this effect being ampliiled by the sealing action of the ashes throughout the lower portion of the furnace.

While any suitable means for rotating the grate assembly may be employed, that which is shown in Fig. l is preferred. A series of enlarged spaced heads 43 are formed on the lower portion of the ring 32 and extend outwardly from the vertical plane of the ring. These spaced heads constitute ratchet teeth and are engageable by a pawl 44 carried by the end of an arm 45 to which reciprocating motion is imparted by any suitable means (not shown). A bracket 46 carried by the wall I4 supports the pawl 44 for engagement with the heads 43. The horizontal leg of the frame member 2| is cut away adjacent the pawl end of the arm to allow the pawl to engage the teeth and these parts are preferably located over the trough 40 so that ashes falling onto the horizontal leg will be carried by the ratchet teethl and deposited, through the cut-away part, in the trough. Reciprocation of the arm 45 will, therefore, produce intermediate rotary movement of the ring 32 and grate 33 about the fire pot. Preferably, the outer end of the horizontal leg of the frame 2| has a short, upwardly extending flange 41 providing a guide for the ring 32.

The direction in which the rim 23 is rotated, in order to effect the interlock thereof with the frame 2|, is preferably determined by the direction in which the grate rotates. That is to say, if' thegrate is driven in a clockwise direction, as indicated by the arrows in Figs. 1 and 2, the rim 23 will be rotated in the same direction or clockwise in order to effect the interlock of the lug 25 with the boss 26. Hence, in operation, rotation of the grate has a constant tendency to drive the lug 25 towardv the shoulder 23, or to maintain engagement of these parts after it has once been effected.

It will be apparent from the foregoing that a' structure has been provided which is exceedingly simple and which may be readily disassembled for inspection, replacement, or repairs. By simply turning the rim to release the interlock, the

rim may be removed after which the entire tuyre structure is accessiblefor removal. The grate 33 may be removed by simply lifting it from its engagement with the ring 32. This permits the grate to be readily replaced by another of the same size or, if deemed desirable due to a change in fuel, a grate of greater or lesser width may be substituted. The advantages of the simple construction, coupled with the advantages of the tuyre structure, produce a stoker which is efflcient and economical in operation.

I claim as my invention:

1. In a tuyre structure for a stoker, the combination ofv a plurality of annular sections arranged one upon the other, means for supporting said sections in vertically spaced relation to each other to provide air emission openings therebetween, means deflning an encircling passageway for delivering air to said openings, and means extending laterally substantially across said passageway intermediate the upper'and lower ends of said tuyre structure to restrict the ilow of air through said openings on one side of said last I mentioned means.

2. In a tuyre structure for a Stoker, the combination of a plurality of annular sections arranged one upon the other, means for supporting said sections in vertically spaced relation to each Ii other to provide air emission openings therebetween, a wall encircling said sections and spaced therefrom to provide a passageway for delivering air through said openings, one of the intermediate sections being of such width as to extend t closely to said wall whereby to define a restriction in said passageway to limit the volume of air flowing to the openings on one side of said widened intermediate section, and means for delivering air under pressure to the passageway on the opposite side of said section.

3. In a stoker, the combination of a vertical tuyre structure having an annular and separately formed rim at the top, a wall encircling said tuyre structure and underlying a portion of said rim to support said rim in place, and a rotating member supported by a flange formed on said wall and closely encircling said rim, said rim and wall having complementary interlocking members thereon engageable by rotation of said rim relative to said wall in the direction of rotation of said rotating member.

4. In a stoker of the underfeed type, the cornbination of a stationary vertical tuyre structure through which fuel is fed upwardly, an annular rotating grate closely encircling the upper portion of said structure and adapted to receive ashes from said structure and to discharge such ashes from its outer periphery, and means on said grate adapted to prevent the movement of large particles of material from said structure outwardly over said grate.

5. In a'stoker of the underfeed type, the combination of a tuyre structure through which fuel is fed, a rotating grate encircling the upper portion of said structure and extending outwardly therefrom, and angularly inclined ribs on said grate arranged to engage large particles of material moving from said structure and return said particles thereto. f

6. In a stoker, the combination of a fire pot, a rotatable member encircling said fire pot and having a peripheral edge over which ashes discharged from said fire pot may fall, an enclosing wall spaced about the lower portion of said nre pot and said member and providing therewith a compartment to receive ashes falling over said edge, ash removing means located at one side of said fire pot between said fire pot and enclosing wall, and means carried 'by said rotatable member and facing said wall for conveying ashes which have fallen into said compartment to said ash removing means. y

7. In a stoker of the underfeed type. the combination of a feed trough, a fire pot surmounting said feed trough, a wall enclosing said fire pot and said trough and defining an air chamber, a rotating grate encompassing said fire pot and arranged to discharge consumed residue over the outer peripheral edge thereof, a furnace wall enclosing said retort, said grate having a plurality of closely spaced notches formed in said edge and facing said wall, said furnace wall being spaced from said first mentioned wall to provide an ash receiving compartment underlying said edge of said grate, plates movable with said grate and arranged to engage an excess of ashes accumulating in said compartment, and means located in said compartment for removing ashes therefrom as said ashes are delivered thereto by said plates.

8. In a. stoker of the underfeed type, the combination of an upwardly opening fire pot, the upper peripheral edge of said pot having an external flange, a plurality of vertically superimposed rings mounted on said fiange and defining tuyre openings, said openings converging in size toward their outlets. an annular rim resting upon the upper one of said rings and defining a plurality of tuyre openings therewith, a base wall encircling said fire pot, a cylindrical wall mounted on said base wall and encircling said rings, said walls defining an air chamber in communication with said openings, the underside of said 'rim being formed with an annular groove receiving the upper edge of said cylindrical wall. and a grate structure mounted for rotation about said rim and extending upwardly and outwardly therefrom.

9. In a stoker of the underfeed type, the combination of an upwardly opening fire pot, the upper peripheral edge of said pot having an external fiange, a plurality of vertically superimposed rings mounted on said flange and defining tuyre openings, an annular rim resting upon the upper one of said rings and defining a plurality of tuyre openings therewith, a base wall encircling said fire pot, a cylindrical wall mounted on said base wall and encircling said rings, said walls defining an air chamber in communication with said openings, said rim resting on said cylindrical wall, a grate structure mounted for rotation aboutl said rim and extending upwardly and outwardly therefrom, and a plurality of elongated ribs on the upper face of said grate structure, said ribs being angularly disposed with respect to the radius in a direction to return unconsumed fuel from said grate structure to said rim.

10. In a stoker, in combination, a centrally located fire pot, a tuyre structure mounted on said fire pot, a wall encircling said tuyre structure and defining an air chamber thereabout, said wall being formed with a peripheral fiange on the exterior defining an upwardly opening track, a cylindrical member loosely encircling said wall and rotatably mounted in said track, and a plurality of peripherally spaced radially extending paddles on the exterior of said cylindrical member.

11. In a stoker. in combination, a centrally located fire pot. a tuyre structure mounted on said fire pot, a wall encircling said tuyre structure and defining an air chamber thereabout, said wall being formed with a peripheral flange on the exterior defining an upwardly opening track, a cylindrical member loosely encircling said wall and rotatably mounted in said track, a plurality of peripherally spaced outwardly extending padl cylindrical wall mounted on said base wall and.

encircling said rings, said walls defining an air chamber in communication with said openings, said rim resting on said cylindrical wall and projecting outwardly beyond said wall, interlocking means for detachably securing said rim to said cylindrical wall, said cylindrical wall being formed about its outer periphery with an outwardly opening annular track, a cylindrical member loosely encircling said cylindrical wall and rotatably mounted on said track, said cylindrical member partially underlying the outer peripheral edge of said rim, and a plurality of ash paddles on the exterior of said cylindrical member.

13. In an underieed stoker, the combination of a vertically disposed tuyre structure comprising a plurality of superimposed rings defining a plurality of annularly and vertically spaced air inlet openings, said rings in the lower portion of said structure defining relatively large air inlet openings and in the upper portion of said structure defining relatively small air inlet openings, means defining an air chamber about said structure in communication with said openings, an air flow restriction in said chamber between said upper and lower portions of said structure, and means for supplying air under pressure to said chamber below said restriction.

14. In a fire pot for a stoker of the underfeed type comprising, in combination, a trough having an annular upwardly opening face, a tuyre structure supported by said trough above said face and comprising a plurality of superimposed ring sections, a vertical annular wall encircling said tuyre structure and extending above said structure, an annular rim supported on the top of said wall and extending at its inner periphery into the upper end of said wall into cooperative relation with the top of said tuyre structure, and complementary interengaging means formed on said rim and the interior of said wall and operable upon relative rotation to detachably secure said wall and said rim together.

WARREN DEAN BURTON. 

